Structure, electrical and magnetic properties, and the origin of the room temperature ferromagnetism in Mn-implanted Si

Orlov, A. F.; Granovsky, A. B.; Balagurov, L. A.; Kulemanov, I. V.; Parkhomenko, Yu. N.; Перов, Н. С.; Ганьшина, Е. А.; Бублик, В. Т.; Щербачев, К. Д.; Kartavykh, A. V.; Vdovin, V. I.; Sapelkin, A.; Saraikin, V. V.; Agafonov, Yu. A.; Зиненко, В. И.; Рогалев, А.; Smekhova, A.

doi:10.1134/s1063776109100069

Cited by 15 publications

(20 citation statements)

References 16 publications

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“…(15) indicates that the vectors ϕ and S are parallel (antiparallel) to each other for κ < 0 (κ > 0). Inserting expression (15) for S(r) into Eq. (14), we include terms up to the fourth power in the order parameter ϕ in F d .…”

Section: Effect Of Quenched Disorder On the Fm Transition In The mentioning

confidence: 99%

“…The authors of Ref. 15 were even compelled to suppose that the high-temperature ferromagnetism, detected in ion-implanted samples, is connected neither with the Mn dopant atoms nor with the MnSi 1.7 intermetallic nanometer-sized phase and is rather caused by structural defects of the silicon lattice (for example, dangling bonds with uncoupled electrons), which occur in the process of preparation of the alloy. 16 As a matter of fact, there exist very serious obstacles to interpreting the high-temperature FM ordering in Si:Mn alloys within the framework of the standard RKKY/Zener-type model of indirect exchange coupling between the local moments of Mn atoms diluted in the Si matrix, on account of the fact that, in Si:Mn materials, the dopant has a pronounced tendency toward the formation of silicide precipitates.…”

Section: Introductionmentioning

confidence: 99%

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High-temperature ferromagnetism in Si:Mn alloys

et al. 2011

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A possible mechanism for high-temperature ferromagnetic order in Si:Mn alloys is proposed. These materials, which are semiconducting or metallic, depending on the Mn content, are suggested to undergo phase separation. In the phase-separated state, again depending on the Mn content, Mn atoms can be gathered within nanometer-sized particles or micrometer-sized islands composed of the MnSi 2−z precipitate with z ≈ (0.25-0.30), which are embedded in the Mn-poor silicon matrix. We consider the MnSi 2−z precipitate to be the MnSi 1.7 silicide host containing a certain amount of magnetic defects associated with unbound Mn 3d orbitals. The MnSi 1.7 silicide is considered to be a weak itinerant ferromagnet, where sizable spin fluctuations (paramagnons) exist far above its intrinsic Curie temperature, leading to a strong enhancement of the exchange coupling between the local moments of the defects. As a result, a significant enhancement of the temperature of onset of long-range order among the local moments may be achieved. We associate this temperature with the global Curie temperature of the precipitate. A phenomenological model is developed to determine the spatial structures and characteristics of ferromagnetic order for the cases of a bulk precipitate and of precipitate particles of various shapes. Moreover, allowing for the presence of strong quenched disorder in the precipitate, we describe short-range ferromagnetic order in the system. Experimental data on Si:Mn alloys are interpreted on the basis of our theoretical results.

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Section: Effect Of Quenched Disorder On the Fm Transition In The mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

High-temperature ferromagnetism in Si:Mn alloys

et al. 2011

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“…However, the physical mechanism of the formation of magnetic properties of these DMSs is far from being well understood. [8][9][10][11] For instance, in Ge 1−x Mn x the coexistence of isolated Mn atoms, Mn-rich clusters, and Mn 5 Ge 3 nanoparticles, dispersed across the Ge host, makes the magnetic behavior of the system extremely complex. [12][13][14] Currently, the technique of δ doping allows DMSs of high quality and precisely controlled composition to be grown in the form of so-called digital magnetic alloys (DMAs).…”

Section: Introductionmentioning

confidence: 99%

Intralayer magnetic ordering in Ge/Mn digital alloys

et al. 2011

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We present a first-principles investigation of the electronic properties of Ge/Mn digital alloys obtained by the insertion of Mn monolayers in the Ge host. The main attention is devoted to the study of the magnetic properties of the Mn layers for various types of ordering of the Mn atoms. Depending on the type of Mn position three different structures are considered: substitutional, interstitial, and combined substitutional-interstitial. In all three cases numerical structural relaxation of the atomic positions has been performed. We find that the intralayer exchange parameters depend strongly on the crystal structure. For the substitutional and interstitial types of structure the stable magnetic order was found to be ferromagnetic. For the mixed substitutional-interstitial structure the ferromagnetic configuration appears unstable and a complex ferrimagnetic structure forms. The spin-wave excitations are calculated within the Heisenberg model. The critical temperatures of the magnetic phase transitions are determined using Monte Carlo simulations with interatomic exchange parameters obtained for two different magnetic reference states: a ferromagnetic and a disordered local moment state.

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“…There have been several attempts to measure XMCD in Mn implanted Si but they were unsuccessful. E.g., Orlov et al, 2009 reported on EXAFS and XMCD measurements at the Mn K edge for the sample annealed at 850°C and showed that the Mn 4 Si 7 or other similar phases were formed but the dichroic Mn XMCD signal was not observed.…”

Section: Resultsmentioning

confidence: 99%

Structural and magnetic properties of Mn+ implanted silicon crystals studied using X-ray absorption spectroscopy techniques

Wolska

Klepka

Ławniczak-Jabłońska

et al. 2011

Radiation Physics and Chemistry

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The implantation of Mn ions into two Si substrates with different doping (P or B), resistivity and oxygen content was performed at the low and high substrate temperatures. Different post implantation processing was carried out to study its influence on the structural and magnetic properties of these samples. The local order around the Mn atoms was characterized by X-ray absorption fine structure techniques and the magnetic properties of the Mn ionic cores were determined by means of X-ray magnetic circular dichroism measurements. The results are discussed in relation to the structural and macroscopic magnetic properties. It is shown that the amorphous matrix speeds up the formation of MnSi x inclusions. However, the existence of inclusions or the type of electrically active dopants is not directly related to the magnetic properties. Therefore, in the performed studies, the importance of structural defects on the magnetic properties was confirmed. A localized magnetic moment carried by the Mn ionic cores could not be detected by means of dichroic measurements.

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Structure, electrical and magnetic properties, and the origin of the room temperature ferromagnetism in Mn-implanted Si

Cited by 15 publications

References 16 publications

High-temperature ferromagnetism in Si:Mn alloys

High-temperature ferromagnetism in Si:Mn alloys

Intralayer magnetic ordering in Ge/Mn digital alloys

Structural and magnetic properties of Mn+ implanted silicon crystals studied using X-ray absorption spectroscopy techniques

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